Elbow flexion strength and contractile activity after partial ulnar nerve or intercostal nerve transfers for brachial plexus injuries

Myoelectric performance of the reconstructed elbow flexor in patients with brachial plexus injuries

Traumatic adult brachial plexus injury is a debilitating injury. Myoelectric exoskeletons are functional tools for restoring elbow flexion. Electromyography signals are used for exoskeleton control, but a characterization specific to the traumatic adult brachial plexus injury population has yet to be performed. This study evaluated if adult patients with traumatic brachial plexus injury and a reconstructed elbow flexor can control a myoelectric exoskeleton. Adult patients who underwent surgical intervention to restore elbow flexion with traumatic brachial plexus injury were recruited for this cross-sectional study. The processed elbow flexor muscle signal and activation thresholds were used to evaluate criteria for exoskeleton control algorithm development. A single activation threshold can be utilized for exoskeleton control, but the calibration routine should consider the resting signal for both extended and flexed elbow positions. The data indicated a 'settle-time' following contraction is needed to prevent unintentional movement of the exoskeleton. All patients activated their elbow flexor above the activation threshold in the supported, flexed position. However, there were different abilities to generate multiple, discrete signals. These results were not specific to surgery, nerve implemented for reconstruction, or post-operative recovery time. Patients with a brachial plexus injury and a reconstructed elbow flexor demonstrated subject-specific capabilities for exoskeleton control.

Re-Evaluation of the Indications for the Camitz Procedure in Severe Carpal Tunnel Syndrome

PURPOSE

The modified Camitz procedure has been used to improve thumb opposition in patients with severe carpal tunnel syndrome (CTS), although its indications remain controversial. This study compared the functional recovery of thumb opposition following carpal tunnel release with and without a concomitant Camitz procedure. We used the Carpal Tunnel Syndrome Instrument questionnaire (CTSI) and the compound muscle action potential of the abductor pollicis brevis (APB-CMAP) to assess the recovery.

METHODS

Five hundred sixty-seven hands underwent surgical treatment for CTS following electrophysiologic studies and the CTSI. The procedures included carpal tunnel release (either endoscopic carpal tunnel release [ECTR] or open carpal tunnel release [OCTR]) and OCTR with a Camitz procedure. One hundred thirty-six patients with absent preoperative APB-CMAP constituted the material of our study. The CTSI and APB-CMAP recoveries between the "ECTR/OCTR group" and the "Camitz group" were compared before surgery and at three, six, and 12 months after surgery.

RESULTS

There were no statistically significant differences in recovery between the "ECTR/OCTR group" and the "Camitz group" according to the three scales of CTSI (symptom severity scale, functional state scale, and FS-2 item, buttoning clothes: an alternative test of thumb opposition) and the APB-CMAP.

CONCLUSION

Carpal tunnel release procedures resulted in the useful recovery of thumb opposition without the need for Camitz, even if APB-CMAP did not fully recover. The action of the other synergistic muscles acting on the thumb and the sensory recovery may have contributed to the recovery of thumb opposition. The Camitz procedure also may be only rarely indicated for hands affected by severe CTS.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Single versus double fascicular transfer for brachial plexus injuries: a systematic review and meta-analysis with meta-regression

The primary objective of this review was to assess whether double fascicular transfer has superior outcomes compared with single fascicular transfer for reanimation of elbow flexion. In total, 58 studies including 1388 patients (mean age 29 years [SD 8]) were included. Subgroup analysis comparing the severity of brachial plexus injury (C5-C6, C5-C7, C5-C8) showed no significant difference in the recovery of MRC grade 3 and 4. The aggregated mean Disabilities of Arm, Shoulder and Hand score was 38 for the single fascicular transfer group and 27 for the double fascicular transfer group. Meta-regression controlling for level of injury showed that double fascicular transfer and C5-C6 injury were significant predictors of achieving MRC grade 3, while double fascicular transfer and shorter duration of surgical delay were significant predictors of achieving MRC grade 4. When controlling for the level of injury, double fascicular transfer is associated with a greater likelihood of achieving MRC grade 3 and 4 compared to single fascicular transfer. Overall donor site morbidity was not significantly different between single fascicular transfer and double fascicular transfer.

The recovery and independence of elbow flexion and forearm supination after Oberlin II transfer in brachial plexus injuries: a long term follows up study

PURPOSE

The Oberlin II double fascicular nerve transfer has been evaluated extensively for objective outcomes for elbow flexion in brachial plexus injuries (BPI). However, there is limited information available on the recovery pattern of supination and patient-reported activity in the long-term. Our study aimed to assess the functional results with a minimum of five years of follow-up.

METHODS

We evaluated patients with a minimum of five years after the Oberlin II procedure for post-traumatic BPI. They were evaluated using MRC grading, range of active movements, QuickDASH score and activity to check elbow flexion and forearm supination independent of finger and wrist flexion.

RESULTS

18 out of 26 patients responded with a mean follow-up of 79.4 months (range: 61-98). 16 (88.9%) (p < 0.000) patients recovered to achieve active elbow flexion and forearm supination of either MRC grade 3 power or more. The average range of active elbow flexion was 113.9° (range: 0-140°) and active supination was 67.8° (0-90°). Patients who achieved grade 3 flexion or higher were found to regain supination after a delay. The recovery continues even after two years of surgery. The mean QuickDASH score was 21.8 (range: 2.3-63.6). There's a significant inverse correlation between QuickDASH with both flexion and supination (p < .001 and < 0.05). 15 patients (83.3%) could demonstrate a dissociation of elbow and forearm movements from digital and wrist movements.

CONCLUSION

Our study demonstrated reliable functional results with independent elbow flexion, forearm supination and acceptable patient-reported outcomes for Oberlin II procedure in BPI.

Adult traumatic brachial plexus injuries: advances and current updates

Nerve grafting, tendon transfer and joint fusion are routinely used to improve the upper limb function in patients with brachial plexus palsies. Newer techniques have been developed that provide additional options for reconstruction. Nerve transfer is a tool for restoring upper limb function in total root avulsions where nerve grafting is not possible. In partial brachial plexus injuries, nerve transfers can greatly improve shoulder, elbow, wrist and hand function. Intraoperative electrical stimulation can be used to diagnose precisely which nerve is injured and to choose which nerve fascicles should be transferred. Finally, measuring the postoperative outcome can improve the evaluation of our techniques. The aim of this article was to present the current techniques used to treat patients with brachial plexus injury.

Current perspectives on peripheral nerve repair and management of the nerve gap

From the first surgical repair of a nerve in the 6th century, progress in the field of peripheral nerve surgery has marched on; at first slowly but today at great pace. Whether performing primary neurorrhaphy or managing multiple large nerve defects, the modern nerve surgeon has an extensive range of tools, techniques and choices available to them. Continuous innovation in surgical equipment and technique has enabled the maturation of autografting as a gold standard for reconstruction and welcomed the era of nerve transfer techniques all while bioengineers have continued to add to our armamentarium with implantable devices, such as conduits and acellular allografts. We provide the reader a concise and up-to-date summary of the techniques available to them, and the evidence base for their use when managing nerve transection including current use and applicability of nerve transfer procedures.

Evaluation of muscle strength following peripheral nerve surgery: A scoping review

Peripheral nerve injury (PNI) can result in devastating loss of function, often with poor long-term prognosis. Increased use of peripheral nerve surgical techniques (eg, nerve transfer, nerve grafting, and nerve repair) has resulted in improved muscle strength and other functional outcomes in patients with PNI. Muscle strength has largely been evaluated with the British Medical Research Council (MRC) scale. MRC is convenient to use in clinical settings, but more robust measures of muscle function are necessary to fully elucidate patient recovery. This scoping review aims to examine alternative instruments used to assess muscle function in studies of peripheral nerve surgery for PNI of the upper and lower limbs. A scoping review was conducted using Ovid MEDLINE, CINAHL, EMBASE, and PubMed databases in May and December of 2020, yielding a total of 20 studies pertaining to the review question. Studies pertaining to handheld dynamometry, grip and pinch dynamometry, Rotterdam Intrinsic Hand Myometers, isokinetic dynamometry, ultrasonography, and electromyography were reviewed. We provide a synopsis of each method and current clinical applications and discuss potential benefits, disadvantages, and areas of future research.

Optimal Donor Nerve to Restore Elbow Flexion After Traumatic Brachial Plexus Injury: A Systematic Review and Meta-Analysis

BACKGROUND

Traumatic brachial plexus injuries (BPIs) often lead to devastating upper extremity deficits. Treatment frequently prioritizes restoring elbow flexion through transfer of various donor nerves; however, no consensus identifies optimal donor nerve sources.

OBJECTIVE

To complete a meta-analysis to assess donor nerves for restoring elbow flexion after partial and total BPI (TBPI).

METHODS

Original English language articles on nerve transfers to restore elbow flexion after BPI were included. Using a random-effects model, we calculated pooled, weighted effect size of the patients achieving a composite motor score of ≥M3, with subgroup analyses for patients achieving M4 strength and with TBPI. Meta-regression was performed to assess comparative efficacy of each donor nerve for these outcomes.

RESULTS

Comparison of the overall effect size of the 61 included articles demonstrated that intercostal nerves and phrenic nerves were statistically superior to contralateral C7 (cC7; P = .025, <.001, respectively) in achieving ≥M3 strength. After stratification by TBPI, the phrenic nerve was still superior to cC7 in achieving ≥M3 strength (P = .009). There were no statistical differences among ulnar, double fascicle, or medial pectoral nerves in achieving ≥M3 strength. Regarding M4 strength, the phrenic nerve was superior to cC7 (P = .01) in patients with TBPI and the ulnar nerve was superior to the medial pectoral nerve (P = .036) for partial BPI.

CONCLUSION

Neurotization of partial BPI or TBPI through the intercostal nerve or phrenic nerve may result in functional advantage over cC7. In patients with upper trunk injuries, neurotization using ulnar, median, or double fascicle nerve transfers has similarly excellent functional recovery.

Does the Score on the MRC Strength Scale Reflect Instrumented Measures of Maximal Torque and Muscle Activity in Post-Stroke Survivors?

It remains unknown whether variation of scores on the Medical Research Council (MRC) scale for muscle strength is associated with operator-independent techniques: dynamometry and surface electromyography (sEMG). This study aimed to evaluate whether the scores of the MRC strength scale are associated with instrumented measures of torque and muscle activity in post-stroke survivors with severe hemiparesis both before and after an intervention. Patients affected by a first ischemic or hemorrhagic stroke within 6 months before enrollment and with complete paresis were included in the study. The pre- and post-treatment assessments included the MRC strength scale, sEMG, and dynamometry assessment of the triceps brachii (TB) and biceps brachii (BB) as measures of maximal elbow extension and flexion torque, respectively. Proprioceptive-based training was used as a treatment model, which consisted of multidirectional exercises with verbal feedback. Each treatment session lasted 1 h/day, 5 days a week for a total 15 sessions. Nineteen individuals with stroke participated in the study. A significant correlation between outcome measures for the BB (MRC and sEMG p = 0.0177, ρ = 0.601; MRC and torque p = 0.0001, ρ = 0.867) and TB (MRC and sEMG p = 0.0026, ρ = 0.717; MRC and torque p = 0.0001, ρ = 0.873) were observed post intervention. Regression models revealed a relationship between the MRC score and sEMG and torque measures for both the TB and BB. The results confirmed that variation on the MRC strength scale is associated with variation in sEMG and torque measures, especially post intervention. The regression model showed a causal relationship between MRC scale scores, sEMG, and torque assessments.

Volumetric MRI is a promising outcome measure of muscle reinnervation

The development of outcome measures that can track the recovery of reinnervated muscle would benefit the clinical investigation of new therapies which hope to enhance peripheral nerve repair. The primary objective of this study was to assess the validity of volumetric Magnetic Resonance Imaging (MRI) as an outcome measure of muscle reinnervation by testing its reproducibility, responsiveness and relationship with clinical indices of muscular function. Over a 3-year period 25 patients who underwent nerve transfer to reinnervate elbow flexor muscles were assessed using intramuscular electromyography (EMG) and MRI (median post-operative assessment time of 258 days, ranging from 86 days pre-operatively to 1698 days post- operatively). Muscle power (Medical Research Council (MRC) grade) and Stanmore Percentage of Normal Elbow Assessment (SPONEA) assessment was also recorded for all patients. Sub-analysis of peak volitional force (PVF), muscular fatigue and co-contraction was performed in those patients with MRC > 3. The responsiveness of each parameter was compared using Pearson or Spearman correlation. A Hierarchical Gaussian Process (HGP) was implemented to determine the ability of volumetric MRI measurements to predict the recovery of muscular function. Reinnervated muscle volume per unit Body Mass Index (BMI) demonstrated good responsiveness (R² = 0.73, p < 0.001). Using the temporal and muscle volume per unit BMI data, a HGP model was able to predict MRC grade and SPONEA with a mean absolute error (MAE) of 0.73 and 1.7 respectively. Muscle volume per unit BMI demonstrated moderate to good positive correlations with patient reported impairments of reinnervated muscle; co- contraction (R² = 0.63, p = 0.02) and muscle fatigue (R² = 0.64, p = 0.04). In summary, volumetric MRI analysis of reinnervated muscle is highly reproducible, responsive to post-operative time and demonstrates correlation with clinical indices of muscle function. This encourages the view that volumetric MRI is a promising outcome measure for muscle reinnervation which will drive advancements in motor recovery therapy.